Whole-House Water Filters
Richard Trethewey explains what to look for when buying a whole-house water filter
“Boil-water” alerts, lead in water pipes, PCB contamination: I don’t think the filter on my kitchen-sink faucet could do the job. Do I need a filter system for the entire house?
—Susan slack, Pittsfield, MA
You might be surprised to know that there are faucet-mounted filters that can remove lead, PCBs, nasty bacterial cysts such as giardia or cryptosporidium, and even pesticides and pharmaceuticals. If you just want to upgrade your existing faucet filter—your least expensive filtering option—then look for one certified to meet NSF/ANSI 53 and 401, the most stringent standards for removing heavy metals and trace contaminants from water.
The good thing about these point-of-use filters is that they purify water only for drinking or cooking, not washing clothes and dishes, flushing toilets, or irrigating the lawn. But you do have to be diligent about replacing filters fairly frequently—every 100 gallons or so.
For a less obtrusive filtering setup, consider one that mounts under the sink. The extra space there means these point-of-use filters can be bigger, more specialized, and won’t need changing as frequently. Most deliver water through a dedicated faucet. Look for filters that meet the 53 and 401 standards and that have a 0.75-gallon-per-minute (gpm) delivery rate through their faucets. That’s not the high flow of a standard faucet, but it’s 50 percent faster than 0.50-gpm filters.
If you want water that’s chemically pure, with every possible contaminant removed, an under-sink, reverse-osmosis (RO) filter will do the job. Such purity does have its drawbacks, however: a high up-front cost, expensive replacement filters, wasted water due to back-flushing—about 3 to 5 gallons go down the drain for every gallon used—and the extra space taken up by its storage tank. Because RO filters work so slowly, the tank enables a faucet flow of 0.50 gpm. Also, water that comes directly from an RO filter doesn’t taste very good, so get a system with a remineralizer that puts calcium, magnesium, and potassium back into the filtered water before you drink it.
But if a point-of-use filter under the kitchen sink doesn’t seem to offer enough protection, a whole-house filtering system certainly is an option, provided you have the budget to make it happen.
Before you begin, though, have your water tested. You want to know exactly what kinds of problems your water has so that the system can be customized to handle them. The free annual reports from your municipal water authority—assuming that’s the source of your water—give a snapshot of the quality of the water leaving the treatment plant. But the water coming out of your taps may be picking up pollutants on its way from the plant. That’s why it’s important to gather water samples in your house. You can find a state-certified water-testing laboratory by calling EPA’s Safe Drinking Water Hotline (800-426-4791) or going to epa.gov. Such tests, I’m sorry to say, are not free.
When comparing whole-house systems, look for a flow rate of at least 15 gpm, and find out how often filters need to be replaced and how much that will cost. Regular upkeep is the key to making these systems function the way they’re supposed to. If you’re not committed to that task, sign up for a service contract.
Shown: Richard Trethewey inspects a top-of-the-line, whole-house filter installed at the TOH TV Detroit project house in 2017. It includes a descaler, two carbon filters, and an ultraviolet light that kills bacteria.